Various efforts are made to lower on-resistance of a power switching device using a wide-bandgap semiconductor such as silicon carbide (SiC), the on-resistance being one of performance indexes of the power switching device. For example, as disclosed in FIG. 2A of Patent Document 1, in order to lower on-resistance of the switching device, an n-type region with a higher concentration than that in a drift region is formed between p-wells, or an n-type JFET limiting region with a higher concentration than that in the drift region is formed on the lower side of the p-well.
As described, a configuration is known where an n-type region is formed between p-wells in order to lower on-resistance of a switching device, and examples of the performance indexes of a power switching device include a withstand-voltage keeping capability in addition to the on-resistance.
In a case where electric field relaxation due to a structure (terminal structure) of a terminal portion of a switching device is insufficient, withstand voltage and reliability of the switching device are affected; however, conventionally, a configuration which not only reduces on-resistance of a switching device but also improves the withstand-voltage keeping capability of the switching device is not disclosed.